If you are still infected after vaccination, should you continue to get the vaccine? What are the differences between the four domestic vaccines?

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Written by reporter Lai Tianying Edited by Ding Lin

New Media Editor/Chen Xuanzhi

Recently, after a month without any local cases in China, Xi'an, Shaanxi reported a local confirmed case, which was caused by an accidental infection caused by an examiner in the isolation area of ​​the Eighth Hospital of Xi'an who was accidentally exposed in the isolated closed ward. This also reminds us that we still need to maintain personal protection measures after receiving the new crown vaccine, including wearing masks, maintaining social distance, washing hands frequently and other good habits.

Zeng Guang, former chief epidemiologist at the Chinese Center for Disease Control and Prevention, pointed out that the protection rate of the new crown vaccine is not 100%, and vaccination is relatively safe but not absolutely safe. Domestic new crown vaccines have been administered to tens of millions of people at home and abroad, and their safety and effectiveness have been fully confirmed. The public does not need to doubt domestic vaccines because of this one case.

The vaccination of the new coronavirus vaccine is progressing in an orderly manner. At the Beijing Novel Coronavirus Pneumonia Epidemic Prevention and Control Press Conference on March 15, Pang Xinghuo, deputy director of the Beijing Center for Disease Control and Prevention, introduced that as of 12:00 that day, a total of 10.36 million doses of the new coronavirus vaccine had been administered in Beijing, and a total of 6.8 million people had been vaccinated, of which 3.56 million people had completed two doses of vaccination.

At present, four independently developed new crown vaccines have been conditionally approved for marketing in China, including three inactivated vaccines - two from Sinopharm Group (Beijing Biological Vaccine, Wuhan Biological Vaccine), and one from Beijing Sinovac (Beijing Sinovac Biotech Vaccine); and one adenovirus vector vaccine (recombinant new coronavirus vaccine-type 5 adenovirus vector), jointly developed and manufactured by CanSino and the team of Academician Chen Wei of the Chinese Academy of Engineering.

△Photo source: Xinhua News Agency

What are the differences between these COVID-19 vaccines? How to choose and how to make an appointment?

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The four approved vaccines belong to two technical routes

Three of the four vaccines that have been conditionally approved for marketing are inactivated vaccines. Inactivated COVID-19 vaccines are made by chemical and other methods to make the COVID-19 lose its infectivity and replication ability, while retaining the ability to induce an immune response in the human body.

Inactivated vaccines are a traditional preparation method and a mature and reliable vaccine development method. The well-known influenza vaccine, hand, foot and mouth disease vaccine, diphtheria, pertussis and tetanus vaccine, etc. are all inactivated vaccines.

Cao Wei, deputy chief physician of the Department of Infectious Diseases at Peking Union Medical College Hospital, commented in an interview with our reporter: In terms of safety, inactivated vaccines are very safe. However, their disadvantage is that inactivation will destroy some components of the virus and affect the ability to stimulate the body's immune system. Multiple injections are often required to strengthen immunity and achieve a good immune effect. Therefore, most inactivated vaccines require two injections.

The "Vero cells" marked on the three domestically produced inactivated COVID-19 vaccines are the cell lines used to reproduce the virus in large quantities before inactivating the COVID-19. Vero cells were first discovered by Japanese scholars in 1962 and are cells isolated and cultured from the kidney tissue of healthy African green monkeys.

△Photo source: Xinhua News Agency

This type of cell reproduces quickly, is easy to culture, and has stable passage. It can reproduce a large number of master copies of the new coronavirus in a short period of time, which can not only ensure the quality and output of the vaccine, but also be relatively safe. In fact, many common inactivated vaccines are produced using Vero cells, such as influenza vaccine, rabies vaccine, Japanese encephalitis vaccine, etc.

On the other hand, the adenovirus vector vaccine developed under the leadership of Academician Chen Wei implants the gene fragments of the new coronavirus into a safely treated adenovirus, and then injects the assembled adenovirus into the human body to train the immune system to remember the characteristics of the new coronavirus and prevent the new coronavirus that may actually invade.

Cao Wei explained that adenovirus is a very common infection in the human body, and most people may have been infected. At the same time, adenovirus is also a very common vector virus in vaccine technology. Common adenovirus vector vaccines include measles virus and dengue virus vaccines.

△Image source: NetEase Health

Compared with inactivated vaccines, adenovirus vector vaccines are nucleic acid vaccines with a relatively simple production process. They do not require large-scale cultivation of live viruses and then killing them, so the production cycle is shorter than that of inactivated vaccines. In addition, CanSino's new crown vaccine only requires one injection to complete the vaccination, which can improve the efficiency of vaccination.

At present, there are 17 COVID-19 vaccines in the clinical stage in my country, 4 of which have been conditionally approved. In addition to inactivated vaccines and adenovirus vector vaccines, the other three technical routes are basically in the Phase III clinical stage or will soon enter the Phase III clinical stage. Clinical trials need to obtain sufficient clinical research data. Once sufficient data is obtained to prove that the efficacy is in line with the design of the program and that the safety data is acceptable, the applicant can submit an application for listing to the National Medical Products Administration. The National Medical Products Administration will organize the review and complete it as soon as possible to ensure that safe and effective vaccines are listed as quickly as possible.

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Can I choose which vaccine I get? Can I get more than one vaccine?

As a number of domestically developed vaccines have been approved for marketing, some people have begun to wonder: Which vaccine should I choose when getting vaccinated?

△Image source: pnas.org

Currently, the type of vaccine cannot be chosen at will. Mixed vaccinations are not allowed in the injection process. If you have completed a vaccination with a vaccine, you can evaluate it after a certain period of time to observe whether antibodies are produced in the body. However, it is not recommended to vaccinate with other different vaccines at the same time in the short term, and there is no need for this.

On March 15, when the reporter called the Beijing Chaoyang District epidemic prevention and control health service hotline, the staff said that the current injection of the new crown vaccine, Beijing's districts will give priority to the key contact groups designated by the state. The remaining personnel will be vaccinated in an orderly manner according to the notification of their units and districts. "The specific vaccine brand is based on the actual vaccination situation at the vaccination site."

The reporter also consulted the neighborhood committee where he lives (Tiangongyuan Community, Daxing District, Beijing). The person in charge said: Currently, the community requires residents to receive free COVID-19 vaccinations in batches. The brands of vaccines currently injected are mostly Sinovac and Beijing Biological (inactivated vaccines). Each vaccination site is only allocated one of these vaccines, which makes it easier to observe adverse reactions after vaccination.

△Photo source: Xinhua News Agency

Cao Wei also believes that the vaccines from Beijing Sinopharm Biotech and Sinovac Biotech, which are currently common in various vaccination sites, both use the inactivated vaccine route, and the difference between the two vaccines is not very large. However, it is not recommended to take a certain inactivated vaccine as the first shot and then take another inactivated vaccine as the second shot - this may actually increase side effects. Clinical trials are only conducted on one product, and no risk assessment has been conducted on the superposition of two products.

Is there a difference between the effects of inactivated and vector vaccines? Academician Chen Wei pointed out that as long as it is approved by the National Medical Products Administration, its safety and effectiveness are supported by certain data, which means that the potential or known benefits are definitely greater than the potential or known risks. "I think it's the same no matter what vaccine you choose. But if you want to have fewer shots, or want to go abroad or perform a mission after taking one shot, (adenovirus vector vaccine) may be the first choice."

Feng Duojia, president of the China Vaccine Industry Association, also said that the recombinant new coronavirus adenovirus vector vaccine and the inactivated vaccine are different in principles, preparation methods, etc., but the final immune effect is the same.

Academician Chen Wei once said, "Many countries are looking forward to vaccines, but our people can choose whether to get vaccinated or not, and which vaccine to get. I think this is a very happy state."

△Photo source: Reuters

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Online booking platform and vaccination for the elderly are gradually open

At present, all regions have unified online appointment platforms for COVID-19 vaccination. For example, residents in Beijing's Dongcheng, Haidian and other districts can make appointments for COVID-19 vaccinations in the next six days through the WeChat mini-program "Sound Intelligence Health". Vaccine recipients can choose any open vaccination site and time period.

Online appointments can not only ensure the accuracy of the vaccine recipient's information, but also effectively reduce the waiting time at the vaccination site and improve the efficiency of vaccination. The vaccination appointment platform is also linked to the "Beijing Health Code", so that travel information, vaccination status, vaccination information, etc. can be clearly seen.

In addition, many places have recently started to vaccinate the elderly over 60 years old. For example, Beijing has vaccinated some elderly people aged 60 and above who have vaccination needs and are in good physical condition according to the overall arrangements of the country. Yin Weidong, chairman of Sinovac Biotech, said in a recent media interview: As long as the elderly's hypertension is controlled, blood sugar is stable, and medication is normal, they can be vaccinated with the new crown vaccine.

In order to better serve the elderly, some vaccination sites have specially upgraded rescue equipment and medicines, adding blood pressure and blood sugar lowering medicines commonly used by the elderly, as well as blood glucose monitors and other equipment. Before on-site vaccination, staff will also assess the elderly's blood pressure and other conditions, and ask in detail about other health conditions.

In the next step, Beijing will carry out comprehensive vaccination of the elderly in a timely manner according to the national opinions. In addition, based on the progress of vaccine research and development and the results of subsequent clinical trials, Beijing will also arrange vaccination for people under 18 years old in the city in accordance with the unified requirements of the state.

Why is vaccination only available to the elderly recently? Cao Wei believes there are many reasons for this.

First of all, vaccines should have a long testing period, but the COVID-19 vaccine only takes about half a year to a year from research and development to market launch, which is relatively short. Although there is no problem with the development ideas of the COVID-19 vaccine and it has undergone Phase II and Phase III clinical tests, in order to reduce the complexity of clinical research, special groups such as the elderly will be temporarily excluded at the beginning.

Second, the overall domestic epidemic situation has been relatively low, and the whole country is basically a low-risk area, which is different from the situation abroad - in Europe and the United States, the elderly or high-risk groups are the key vaccination groups. Therefore, whether a specific group of people is vaccinated is related to the epidemic pressure of the local epidemic, which reflects that the science of herd immunity not only takes care of personal health, but also requires comprehensive social considerations.

References:

[1] What are the differences between the four domestic COVID-19 vaccines?

baijiahao.baidu.com/s?id=1692932243914266380&wfr=spider&for=pc

[2] Another COVID-19 vaccine has been launched in my country. What are the differences between the two vaccines and how should we choose?

baijiahao.baidu.com/s?id=1693015436512605525&wfr=spider&for=pc

[3] Lu Zengjun, Cao Yimei, Liu Zaixin, et al. Application of adenovirus vectors in gene therapy and vaccine research [J]. Animal Husbandry Market, 2009(03):622-625.

[4] Should I get vaccinated against COVID-19?

360doc.com/content/21/0102/01/12836615_954755740.shtml

[5] Beijing Dongcheng District COVID-19 vaccination appointment system launched

baijiahao.baidu.com/s?id=1693806142338600270&wfr=spider&for=pc

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